Story highlights

Sam Stosur ends 18-year-old Laura Robson's impressive U.S. Open run with a 6-4 6-4 win

Maria Sharapova's impressive record of winning matches that go to three sets in 2012 shows no sign of ending after the Russian beat Nadia Petrova in the U.S. Open fourth round to set up a quarterfinal meeting with Marion Bartoli.

Sharapova won 6-1, 4-6, 6-4, but was rattled by Petrova winning four games in a row that enabled the 19th seed to take the second set and lead 2-0 in the third before an hour and 13 minute rain break.

The No.3 seed took full advantage of the delay, speaking to her father Yuri, before returning to seal a two hour, 14-minute victory to give Sharapova her 11th win in three-set matches in 2012 and her 23rd victory in 24 three-setters since the start of 2011.

"It's a nice statistic," said Sharapova after her last 16 win over her fellow Russian.

"I don't really think about it going into a new third set situation, because every match is different, whether you started slow and came back in the second, or whether you had a letdown in the second.

JUST WATCHED

Take a bow Serena Williams

MUST WATCH

JUST WATCHED

Serena Williams in 7th Wimbledon final

MUST WATCH

Serena Williams in 7th Wimbledon final02:43

"But overall, I always think that no matter how you start the match, it's always how you finish. Whether it's an hour or three hours you're out on the court, I don't want to give up until the last point.

"That's pretty much the mentality I try to have going into a third set."

Having been in the lead in the third set, Petrova found the defeat difficult to take.

"I had been in control in the third set," said the No.19 seed. "I had everything in my hands.

"Maria looked hesitant and she couldn't get a hold of her game. But then after the rain break, actually it went in her favour because she had time to think, regroup, talk to her coach.

"And then she came out completely cool and collected. She started playing big tennis. Unfortunately, luck was on her side."

Frenchwoman Bartoli also had to come from behind to beat the fifth seed Petra Kvitova, but did so in style, winning 12 of 13 games to take a 1-6, 6-2, 6-0 victory.

Earlier on Sunday defending champion Sam Stosur ended 18-year-old Briton Laura Robson's impressive U.S. Open run with a 6-4 6-4 win in the fourth round of the U.S. Open.

Robson, who had beaten Kim Clijsters and Li Na to reach the fourth round, saved eight match points as she came from 5-2 down to get back on serve but Australian Stosur broke again to clinch victory and a match with top seed Victoria Azarenka.

"I'm definitely disappointed," said former Wimbledon junior champion Robson, who will rise from 89th to 75th in the rankings after doing so well at Flushing Meadows. "I felt like I didn't play as well as I did in my last three matches. I just hit too many unforced errors."